Horror of Fang Rock
The Sentarii were an intelligent insectoid species from Sentarion.
Fang Rock was a craggy island situated off of the southern coast of England. (Horror of Fang Rock) Located close to major shipping lanes, it was the site of Fang Rock Lighthouse. (The Secret Lives of Monsters)
In the 1820s, there was a sighting of the mythical Beast of Fang Rock. That night, two people on the island died.
In the 1900s, a Rutan ship landed underwater nearby and a scout emerged. It killed the lighthouse keeper, Ben Travers. This was suspected by Reuben Whormby, another keeper, to be the work of the beast. A fog, created by the Rutan, covered the island. The Fourth Doctor and Leela found themselves on Fang Rock while trying to get to Brighton. They visited the lighthouse.
Henry Palmerdale’s steam yacht crashed due to the fog and the technical failure of the lighthouse. Palmerdale, Harker, James Skinsale and Adelaide Lessage survived and were taken in by the lighthouse keepers. They were all killed by the Rutan, as were Reuben and Vince Hawkins.
The Doctor killed the scout with a makeshift mortar. Leela inspired him to fit the lighthouse with a carbon oscillator, which he used to destroy the Rutan mothership. (Horror of Fang Rock)
Leela later referred to Fang Rock when The Doctor brought her back to Great Britain. (The Darkness of Glass)